Polyphenol exposure of mothers and infants assessed by LC-MS/MS based biomonitoring in breast milk

Exposure to polyphenols is relevant throughout critical windows of infant development, including the breastfeeding phase. However, the quantitative assessment of polyphenols in human breast milk has received limited attention so far, though polyphenols may positively influence infant health. Therefore, a targeted LC-MS/MS assay was developed to investigate 86 analytes representing different polyphenol classes in human breast milk. The sample preparation consisted of liquid extraction, salting out, freeze-out, and a dilution step. Overall, nearly 70% of the chemically diverse polyphenols fulfilled all strict validation criteria for full quantitative assessment. The remaining analytes did not fulfill all criteria at every concentration level, but can still provide useful semi-quantitative insights into nutritional and biomedical research questions. The limits of detection for all analyzed polyphenols were in the range of 0.0041-87 ng*mL-1, with a median of 0.17 ng*mL-1. Moreover, the mean recovery was determined to be 82% and the mean signal suppression and enhancement effect was 117%. The developed assay was applied in a proof-of-principle study to investigate polyphenols in breast milk samples provided by twelve Nigerian mothers at three distinct time points post-delivery. In total, 50 polyphenol analytes were detected with almost half being phenolic acids. Phase II metabolites, including genistein-7-β-D-glucuronide, genistein-7-sulfate, and daidzein-7-β-D-glucuronide, were also detected in several samples. In conclusion, the developed method was demonstrated to be fit-for-purpose to simultaneously (semi-) quantify a wide variety of polyphenols in breast milk. It also demonstrated that various polyphenols including their biotransformation products were present in breast milk and therefore likely transferred to infants where they might impact microbiome development and infant health.

Enhancing microbiome research in sub-Saharan Africa

While there are lighthouse examples of microbiome research in sub-Saharan Africa (SSA), a significant proportion of local researchers face several challenges. Here, we highlight prevailing issues limiting microbiome research in SSA and suggest potential technological, societal, and research-based solutions. We emphasize the need for considerable investment in infrastructures, training, and appropriate funding to democratize modern technologies with a view to providing useful data to improve human health.

The Austrian children's biomonitoring survey 2020 Part B: Mycotoxins, phytotoxins, phytoestrogens and food processing contaminants

This study assessed the levels of environment and food-related exposures in urine of Austrian school children aged six to ten (n = 85) focusing on mycotoxins, phytoestrogens, and food processing by-products using two multi-analyte LC-MS/MS methods. Out of the 55 biomarkers of exposure reported in this study, 22 were quantified in the first void urine samples. Mycotoxins frequently quantified included zearalenone (detection rate 100%; median 0.11 ng/mL), deoxynivalenol (99%; 15 ng/mL), alternariol monomethyl ether (75%; 0.04 ng/mL), and ochratoxin A (19%; 0.03 ng/mL). Several phytoestrogens, including genistein, daidzein, and its metabolite equol, were detected in all samples at median concentrations of 22 ng/mL, 43 ng/mL, and 14 ng/mL, respectively. The food processing by-product 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), was detected in 4% of the samples (median 0.016 ng/mL). None of the investigated samples contained the tested phytotoxins that were rarely considered for human biomonitoring previously (pyrrolizidine alkaloids, tropane alkaloids, aristolochic acids). When relating estimated exposure to current health-based guidance values, 22% of the children exceeded the tolerable daily intake for deoxynivalenol, and the estimated MOE for OTA indicates possible health risks for some children. The results clearly demonstrate frequent low-level (co-)exposure and warrant further exposome-scale exposure assessments, especially in susceptible sub-populations and longitudinal settings.

Mycotoxin exposure biomonitoring in breastfed and non-exclusively breastfed Nigerian children

A multi-specimen, multi-mycotoxin approach involving ultra-sensitive LC-MS/MS analysis of breast milk, complementary food and urine was applied to examine mycotoxin co-exposure in 65 infants, aged 1-18 months, in Ogun state, Nigeria. Aflatoxin M₁ was detected in breast milk (4/22 (18%)), while six other classes of mycotoxins were quantified; including dihydrocitrinone (6/22 (27%); range: 14.0-59.7 ng/L) and sterigmatocystin (1/22 (5%); 1.2 ng/L) detected for the first time. Seven distinct classes of mycotoxins including aflatoxins (9/42 (21%); range: 1.0-16.2 µg/kg) and fumonisins (12/42 (29%); range: 7.9-194 µg/kg) contaminated complementary food. Mycotoxins covering seven distinct classes with diverse structures and modes of action were detected in 64/65 (99%) of the urine samples, demonstrating ubiquitous exposure. Two aflatoxin metabolites (AFM₁ and AFQ₁) and FB₁ were detected in 6/65 (9%), 44/65 (68%) and 17/65 (26%) of urine samples, respectively. Mixtures of mycotoxin classes were common, including 22/22 (100%), 14/42 (33%) and 56/65 (86%) samples having 2-6, 2-4, or 2-6 mycotoxins present, for breast milk, complementary food and urine, respectively. Aflatoxin and/or fumonisin was detected in 4/22 (18%), 12/42 (29%) and 46/65 (71%) for breast milk, complimentary foods and urine, respectively. Furthermore, the detection frequency, median concentrations and occurrence of mixtures were typically greater in urine of non-exclusively breastfed compared to exclusively breastfed infants. The study provides novel insights into mycotoxin co-exposures in early-life. Albeit a small sample set, it highlights transition to higher levels of infant mycotoxin exposure as complementary foods are introduced, providing impetus to mitigate during this critical early-life period and encourage breastfeeding.

Trace analysis of emerging and regulated mycotoxins in infant stool by LC-MS/MS

Infants are sensitive to negative effects caused by food contaminants such as mycotoxins. To date, analytical methods assessing mycotoxin mixture exposure in infant stool are absent. Herein, we present a novel multi-mycotoxin LC-MS/MS assay capable of detecting 30+ analytes including the regulated mycotoxin classes (aflatoxins, trichothecenes, ochratoxins, zearalenone, citrinin), emerging Alternaria and Fusarium toxins, and several key metabolites. Sample preparation consisted of a ‘dilute, filter, and shoot’ approach. The method was in-house validated and demonstrated that 25 analytes fulfilled all required criteria despite the high diversity of chemical structures included. Extraction recoveries for most of the analytes were in the range of 65–114% with standard deviations below 30% and limits of detection between 0.03 and 11.3 ng/g dry weight. To prove the methods’ applicability, 22 human stool samples from premature Austrian infants (n = 12) and 12-month-old Nigerian infants (n = 10) were analyzed. The majority of the Nigerian samples were contaminated with alternariol monomethyl ether (8/10) and fumonisin B₁ (8/10), while fumonisin B₂ and citrinin were quantified in some samples. No mycotoxins were detected in any of the Austrian samples. The method can be used for sensitive human biomonitoring (HBM) purposes and to support exposure and, potentially, risk assessment of mycotoxins. Moreover, it allows for investigating potential associations between toxicant exposure and the infants’ developing gut microbiome.

Analysis of bacterial communities of three cassava-based traditionally fermented Nigerian foods (abacha, fufu and garri)

Globally, cassava is an important food crop that contributes significantly to food security. In Nigeria, cassava can be traditionally processed into abacha (fermented strips), fufu (submerged-fermented porridge) and garri (solid-state fermented farinated granules) for human consumption. Despite the widespread consumption of these foods, there is a major knowledge gap in understanding their core bacterial diversity. This study, therefore, applied next-generation sequencing of 16S rRNA gene to delineate the bacterial diversity in abacha, fufu and garri. Amplicon sequence variants belonging to nine phyla were present in the three foods. Firmicutes dominated the bacterial community of abacha and fufu, whereas, Proteobacteria was the dominant phylum in garri. At genus level taxa, Lactococcus, Lysinibacillus and Pseudomonas dominated the bacterial community in abacha, fufu and garri, respectively. Other dominant phylotypes reported in the foods belonged to Bacillus, Clostridium sensu stricto (cluster 1), Cupriavidus, Enterobacter, Sphingomonas and Staphylococcus. To the best of our knowledge, Clostridium sensu stricto cluster 1 and Lysinibacillus in fufu, and Brevundimonas, Cupriavidus, Sphingomonas and Strenotrophomomas in garri are reported for the first time. Although some potential pathogenic genera were recorded, the foods contained potentially functional species that could be explored to improve artisanal food production, food security and safeguard consumer health.

Dietary Risk Assessment and Consumer Awareness of Mycotoxins among Household Consumers of Cereals, Nuts and Legumes in North-Central Nigeria

This study characterized the health risks due to the consumption of mycotoxin-contaminated foods and assessed the consumer awareness level of mycotoxins in households in two north-central Nigerian states during the harvest and storage seasons of 2018. Twenty-six mycotoxins and 121 other microbial and plant metabolites were quantified by LC-MS/MS in 250 samples of cereals, nuts and legumes. Aflatoxins were detected in all food types (cowpea, maize, peanut and sorghum) except in millet. Aflatoxin B₁ was the most prevalent mycotoxin in peanut (64%) and rice (57%), while fumonisin B₁ occurred most in maize (93%) and beauvericin in sorghum (71%). The total aflatoxin concentration was highest in peanut (max: 8422 µg/kg; mean: 1281 µg/kg) and rice (max: 955 µg/kg; mean: 94 µg/kg), whereas the totals of the B-type fumonisins and citrinin were highest in maize (max: 68,204 µg/kg; mean: 2988 µg/kg) and sorghum (max: 1335 µg/kg; mean: 186 µg/kg), respectively. Citrinin levels also reached 51,195 µg/kg (mean: 2343 µg/kg) in maize. Aflatoxin and citrinin concentrations in maize were significantly (p < 0.05) higher during storage than at harvest. The estimated chronic exposures to aflatoxins, citrinin and fumonisins were high, resulting in as much as 247 new liver cancer cases/year/100,000 population and risks of nephrotoxicity and esophageal cancer, respectively. Children who consumed the foods were the most vulnerable. Mycotoxin co-occurrence was evident, which could increase the health risk of the outcomes. Awareness of mycotoxin issues was generally low among the households.

Fungal Diversity and Aflatoxins in Maize and Rice Grains and Cassava-Based Flour (Pupuru) from Ondo State, Nigeria

Grains and cassava-based foods serve as major dietary sources for many households in Nigeria. However, these foods are highly prone to contamination by moulds and aflatoxins owing to poor storage and vending practices. Therefore, we studied the fungal diversity in maize, cassava-based flour (pupuru), and rice vended in markets from Ondo state, Nigeria, and assessed their aflatoxin levels using an enzyme-linked immunosorbent assay. Molecular analysis of 65 representative fungal isolates recovered from the ground grains and pupuru samples revealed 26 species belonging to five genera: Aspergillus (80.9%), Penicillium (15.4%), and Talaromyces (1.9%) in the Ascomycota; Syncephalastrum (1.2%) and Lichtheimia (0.6%) in Mucoromycota. Aspergillus flavus was the predominant species in the ground grains and pupuru samples. Aflatoxins were found in 73.8% of the 42 representative food samples and 41.9% exceeded the 10 μg/kg threshold adopted in Nigeria for total aflatoxins.

A review of microbes and chemical contaminants in dairy products in sub-Saharan Africa

Animal milk types in sub-Saharan Africa (SSA) are processed into varieties of products using different traditional methods and are widely consumed by households to support nutritional intake and diet. Dairy products contain several microorganisms, their metabolites, and other chemical compounds, some with health benefits and many others considered as potential health hazards. Consumption of contaminated milk products could have serious health implications for consumers. To access the safety of milk products across SSA, studies in the region investigating the occurrences of pathogens as well as chemical compounds such as heat stable toxins and veterinary drug residues in animal milk and its products were reviewed. This is done with a holistic view in light of the emerging exposome paradigm for improving food safety and consumer health in the region. Herein, we showed that several published studies in SSA applied conventional and/or less sensitive methods in detecting microbial species and chemical contaminants. This has serious implications in food safety because the correct identity of a microbial species and accurate screening for chemical contaminants is crucial for predicting the potential human health effects that undermine the benefits from consumption of these foods. Furthermore, we highlighted gaps in determining the extent of viral and parasitic contamination of milk products across SSA as well as investigating multiple classes of chemical contaminants. Consequently, robust studies should be conducted in this regard. Also, efforts such as development cooperation projects should be initiated by all stakeholders including scientists, regulatory agencies, and policy makers to improve the dairy product chain in SSA in view of safeguarding consumer health.

Diversity and toxigenicity of fungi and description of Fusarium madaense sp. nov. from cereals, legumes and soils in north-central Nigeria

Mycological investigation of various foods (mainly cowpea, groundnut, maize, rice, sorghum) and agricultural soils from two states in north-central Nigeria (Nasarawa and Niger), was conducted in order to understand the role of filamentous fungi in food contamination and public health. A total of 839 fungal isolates were recovered from 84% of the 250 food and all 30 soil samples. Preliminary identifications were made, based on macro- and micromorphological characters. Representative strains (n = 121) were studied in detail using morphology and DNA sequencing, involving genera/species-specific markers, while extrolite profiles using LC-MS/MS were obtained for a selection of strains. The representative strains grouped in seven genera (Aspergillus, Fusarium, Macrophomina, Meyerozyma, Neocosmospora, Neotestudina and Phoma). Amongst the 21 species that were isolated during this study was one novel species belonging to the Fusariumfujikuroi species complex, F.madaensesp. nov., obtained from groundnut and sorghum in Nasarawa state. The examined strains produced diverse extrolites, including several uncommon compounds: averantinmethylether in A.aflatoxiformans; aspergillimide in A.flavus; heptelidic acid in A.austwickii; desoxypaxillin, kotanin A and paspalitrems (A and B) in A.aflatoxiformans, A.austwickii and A.cerealis; aurasperon C, dimethylsulochrin, fellutanine A, methylorsellinic acid, nigragillin and pyrophen in A.brunneoviolaceus; cyclosporins (A, B, C and H) in A.niger; methylorsellinic acid, pyrophen and secalonic acid in A.piperis; aspulvinone E, fonsecin, kojic acid, kotanin A, malformin C, pyranonigrin and pyrophen in A.vadensis; and all compounds in F.madaense sp. nov., Meyerozyma, Neocosmospora and Neotestudina. This study provides snapshot data for prediction of food contamination and fungal biodiversity exploitation.

Aflatoxin contamination of maize vended in Ondo state, Nigeria, and health risk assessments

Aflatoxin contamination of maize is a serious food safety problem worldwide. Despite the widespread consumption of maize in Nigeria, there is limited data on aflatoxin contents of maize vended in open markets in Ondo state, Nigeria. A total of 140 maize samples randomly purchased from major markets in four locations in Ondo state, were screened for total aflatoxins using an ELISA method. Exposure and health risk assessments were performed for the maize consumers by the deterministic and Margin of exposure (MOE) approaches, respectively. About 99% of the maize were contaminated with total aflatoxins (range: 0.65–265 µg/kg; mean: 125.9 µg/kg). Aflatoxin levels exceeding the 4 µg/kg set by the European Union for total aflatoxins were found in 88% of the maize whilst more than one half contained at least 100 µg/kg aflatoxins. The average probable daily intake values were 830, 332 and 138 ng/kg bw/day for the average children, adolescent and adult populations, respectively. Consequently, MOEs for the respective populations were 0.20, 0.51 and 1.23, suggesting a high level of health risk for consumers of maize vended in open markets in Ondo state due to high aflatoxin levels. Maize farmers and households in Ondo state need urgent aflatoxin mitigation interventions.

Fungal Diversity and Mycotoxins in Low Moisture Content Ready-To-Eat Foods in Nigeria

Low moisture content ready-to-eat foods vended in Nigerian markets could be pre-packaged or packaged at point of sale. These foods are widely and frequently consumed across Nigeria as quick foods. Despite their importance in the daily diets of Nigerians, a comprehensive study on the diversity of fungi, fungal metabolite production potential, and mycotoxin contamination in the foods has not yet been reported. Therefore, this study assessed the diversity of fungi in 70 samples of low moisture content ready-to-eat foods [cheese balls, garri (cassava-based), granola (a mix of cereals and nuts) and popcorn] in Nigeria by applying a polyphasic approach including morphological examination, genera/species-specific gene marker sequencing and secondary metabolite profiling of fungal cultures. Additionally, mycotoxin levels in the foods were determined by LC-MS/MS. Fungal strains (n = 148) were recovered only from garri. Molecular analysis of 107 representative isolates revealed 27 species belonging to 12 genera: Acremonium, Allophoma, Aspergillus, Cladosporium, Fusarium, Microdochium, Penicillium, Sarocladium, Talaromyces, and Tolypocladium in the Ascomycota, and Fomitopsis and Trametes in the Basidiomycota. To the best of our knowledge Allophoma, Fomitopsis, Microdochium, Tolypocladium, and Trametes are reported in African food for the first time. A total of 21 uncommon metabolites were found in cultures of the following species: andrastin A and sporogen AO1 in Aspergillus flavus; paspalin in A. brunneoviolaceus; lecanoic acid and rugulusovin in A. sydowii; sclerotin A in P. citrinum and Talaromyces siamensis; barceloneic acid, festuclavine, fumigaclavine, isochromophilons (IV, VI, and IX), ochrephilone, sclerotioramin, and sclerotiorin in P. sclerotium; epoxyagroclavine, infectopyron, methylorsellinic acid and trichodermamide C in P. steckii; moniliformin and sporogen AO1 in P. copticola; and aminodimethyloctadecanol in Tolypocladium. Twenty-four mycotoxins in addition to other 73 fungal and plant toxins were quantified in the foods. In garri, cheeseballs, popcorn and granola were 1, 6, 12, and 23 mycotoxins detected, respectively. Deoxynivalenol, fumonisins, moniliformin, aflatoxins and citrinin contaminated 37, 31, 31, 20, and 14% of all food samples, respectively. Overall, citrinin had the highest mean concentration of 1481 μg/kg in the foods, suggesting high citrinin exposures in the Nigerian populace. Fungal and mycotoxin contamination of the foods depend on pre-food and post-food processing practices.

Fungal and plant metabolites in industrially-processed fruit juices in Nigeria

There is scarce data on the mycotoxin profile in retailed fruit juices in Nigeria. Thirty-five industrially-processed fruit juice samples randomly purchased from retailers in Ogun state, Nigeria, were analysed for the presence of > 650 toxic fungal and plant metabolites using a liquid chromatography tandem mass spectrometric method. Only 18 metabolites, including 3-nitropropionic acid, alternariol methylether and emodin, but excluding citrinin, fumonisin B₂, ochratoxin A and patulin, were detected in trace levels in at least one juice sample. Amygdalin, a plant cyanogen, was quantified (2.05-359 µg/L) in 40% of the samples. Although the levels of mycotoxins and toxic plant metabolites found in the juice may be relatively low, daily consumption of juices containing such low levels may contribute to dietary exposures to these natural chemical contaminants in consumers. Fruit juice processors should be encouraged to adhere strictly to good manufacturing practices in order to keep mycotoxins away from the final products.

High-Throughput Sequence Analyses of Bacterial Communities and Multi-Mycotoxin Profiling During Processing of Different Formulations of Kunu, a Traditional Fermented Beverage

Kunu is a traditional fermented single or mixed cereals-based beverage popularly consumed in many parts of West Africa. Presently, the bacterial community and mycotoxin contamination profiles during processing of various kunu formulations have never been comprehensively studied. This study, therefore, investigated the bacterial community and multi-mycotoxin dynamics during the processing of three kunu formulations using high-throughput sequence analysis of partial 16S rRNA gene (hypervariable V3-V4 region) and liquid chromatography tandem mass spectrometry (LC-MS/MS), respectively. A total of 2,303 operational taxonomic units (OTUs) were obtained across six processing stages in all three kunu formulations. Principal coordinate analysis biplots of the Bray-Curtis dissimilarity between bacterial communities revealed the combined influences of formulations and processing steps. Taxonomically, OTUs spanned 13 phyla and 486 genera. Firmicutes (phylum) dominated (relative abundance) most of the processing stages, while Proteobacteria dominated the rest of the stages. Lactobacillus (genus taxa level) dominated most processing stages and the final product (kunu) of two formulations, whereas Clostridium sensu stricto (cluster 1) dominated kunu of one formulation, constituting a novel observation. We further identified Acetobacter, Propionibacterium, Gluconacetobacter, and Gluconobacter previously not associated with kunu processing. Shared phylotypes between all communities were dominated by lactic acid bacteria including species of Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, and Weissella. Other shared phylotypes included notable acetic acid bacteria and potential human enteric pathogens. Ten mycotoxins [3-Nitropropionic acid, aflatoxicol, aflatoxin B1 (AFB1), AFB2, AFM1, alternariol (AOH), alternariolmethylether (AME), beauvericin (BEAU), citrinin, and moniliformin] were quantified at varying concentrations in ingredients for kunu processing. Except for AOH, AME, and BEAU that were retained at minimal levels of < 2 μg/kg in the final product, most mycotoxins in the ingredients were not detectable after processing. In particular, mycotoxin levels were substantially reduced by fermentation, although simple dilution and sieving also contributed to mycotoxin reduction. This study reinforces the perception of kunu as a rich source of bacteria with beneficial attributes to consumer health, and provides in-depth understanding of the microbiology of kunu processing, as well as information on mycotoxin contamination and reduction during this process. These findings may aid the development of starter culture technology for safe and quality kunu production.

Phylogenetic analyses of bacteria associated with the processing of iru and ogiri condiments

Analysis of the bacterial community dynamics during the production of traditional fermented condiments is important for food safety assessment, quality control and development of starter culture technology. In this study, bacteria isolated during the processing of iru and ogiri, two commonly consumed condiments in Nigeria, were characterized based on phylogenetic analyses of the bacterial 16S rRNA gene. A total of 227 isolates were obtained and clustered into 12 operational taxonomic units (OTUs) based on 97% 16S rRNA gene similarity. The OTUs spanned three phyla (Firmicutes, Actinobacteria and Proteobacteria), and nine genera: Acinetobacter, Aerococcus, Bacillus, Enterococcus, Enterobacter, Lysinibacillus, Micrococcus, Proteus and Staphylococcus. OTUs closely related to species of Bacillus dominated the processing stages of both condiments. Although no single OTU occurred throughout iru processing stages, an OTU (mostly related to B. safensis) dominated the ogiri processing stages indicating potentials for the development of starter culture. However, other isolates such as those of Enterococcus spp. and Lysinibacillus spp. may be potential starters for iru fermentation. Presumptive food-borne pathogens were also detected at some stages of the condiments' processing, possibly due to poor hygienic practices.

SIGNIFICANCE AND IMPACT OF THE STUDY

Iru and ogiri are important condiments used for flavour enhancement in foods and serve as protein substitutes in diets among rural populations across West Africa. Consumption of these condiments is growing, reinforcing the need to scale up their production. Production of these condiments includes spontaneous fermentation, which often leads to inconsistent product quality and unguaranteed safety. This study has demonstrated the bacterial succession in iru and ogiri processing and highlights species that could be selected and exploited for starter culture development. This study provides a starting point to produce quality and microbiologically safe iru and ogiri condiments.

Urinary aflatoxin exposure monitoring in rural and semi-urban populations in Ogun state, Nigeria

Aflatoxins are a major class of fungal toxins that have food safety importance due to their economic and health impacts. This pilot aflatoxin exposure biomonitoring study on 84 individuals was conducted in a rural (Ilumafon) and a semi-urban community (Ilishan Remo) of Ogun state, Nigeria, to compare aflatoxin exposures among the two population cohorts. First morning urine samples were obtained from the participants, and the urinary aflatoxin M₁ (AFM₁) levels were measured by a quantitative Helica Biosystems Inc. ELISA kit assay. About 99% (83 out of 84) of the urine samples had detectable AFM₁ levels in the range of 0.06 to 0.51 ng mL^-1 (median: 0.27 ng mL^-1). The mean urinary AFM₁ levels were significantly (p = 0.001) higher in the semi-urban population (0.31 ± 0.09 ng mL^-1) compared to the rural population (0.24 ± 0.07 ng mL^-1). There were, however, no significant differences in mean urinary AFM₁ levels of males and females, and among children, adolescents and adults. This study indicates high aflatoxin exposure to the extent of public health concerns in the studied populations. Thus, more efforts are required for aflatoxin exposure monitoring and control in high-risk regions.